The present invention provides a system approach to digital advertisement insertion in a television signal or the like that is consistent for both satellite television uplinks and cable television headends. The invention is particularly adapted for use with analog television signals that are subsequently digitized, e.g., using an MPEG-2 compression system.
Analog television signals are commonly broadcast over satellite links to headends of cable television networks or affiliate sites of Broadcaster""s network. The term xe2x80x9cheadendxe2x80x9d is used hereafter even though the same applies to an affiliate site. Programming signals from different cable or television networks (e.g., CNN, ABC) are provided with cue tones, which signal the start and end of a message break period during which commercials may be run. Each network generally has a unique cue tone which occurs a few seconds before the start and end times of the insertion window.
For example, the network signal may leave blank air time during this period to allow the headend to insert commercials of local interest when the cue tones are detected. Typically however, the network""s national commercial may get replaced by a local commercial if the window or part of it allows such replacement and a replacement is available locally. The commercials may be paid advertisements, unpaid public service announcements, or the like. The content may be video, audio, and/or other data (e.g., HTML pages with hyperlinks, etc.). Note that in the data-only case, the original programming (with or without a national ad) may be left intact with locally originated data added as supplementary information to the original content. For example, web-supported ads, with locally generated web pages, can be facilitated. The bandwidth requirements for insertion of such data are minimal. Regardless, the required bandwidth would have been allocated a priori.
The cable headend operator may use automated equipment that controls video tape players and positions the local commercial or other messages for playback and insertion when cued at the proper time.
Or, the network signal may include its own commercials which can optionally be electronically pre-emptied by the local insertions.
Typically, the message break (window) is one or two minutes in duration, which allows a number of commercials. Commercial or xe2x80x9cspotxe2x80x9d durations vary. Some are fifteen seconds or less, while others are thirty seconds, sixty seconds, etc.
Currently, however, broadcasting of digital audiovisual content has become increasingly popular in cable networks and soon in TV broadcast networks, and is expected to gradually supplant the analog schemes. Various standards have been developed for the communication of digital audiovisual content such as the MPEG-2 standard. Moreover, MPEG-2 provides a framework, albeit incomplete, for splicing of transport streams, discussed in xe2x80x9cRevised Text for ITU-T Recommendation H.222.051 ISO/IEC 13818-1, Information technologyxe2x80x94Generic coding of moving pictures and associated audio information: Systems,xe2x80x9d ISO/IEC JTC 1/SC 29, Apr. 27, 1995, pp. 135-138 (Annex Lxe2x80x94Splicing Transport Streams).
The MPEG-2 standard provides syntax elements that are relevant to splicing in a transport packet adaptation field. The syntax elements include a splicing_point_flag, which is a single bit that indicates whether a splice_countdown field is present. The splice_countdown field is used to count down how many packets of the same packet identifier (PID) occur before the splice point. Additionally, the transport stream packet in which the splice_countdown field value reaches zero is called the splicing packet. The splicing point is located immediately after the last byte of the splicing packet.
However, some of the past proposals to complement the MPEG-2 capability required decoding of several of the data layers in the digital transport stream to obtain information regarding timing (e.g., time stamp values) and buffer fullness status to allow a successful commercial insertion. In another approach, the entire data stream, including video and audio, is decoded in a manner that maintains some of the original encoding parameters. Then, a commercial is inserted into the decoded stream, and the stream is re-encoded using the conveyed parameters which were obtained during decoding. The intent was to enable more efficient re-encoding when compared to re-encoding without these parameters.
Moreover, such digital splicing schemes do not take into account the operational requirements associated with cue tones in the analog domain, nor the various operations that may be applied to the stream prior to commercial insertion, e.g., add/drop multiplexing.
Additionally, there already exists an installed base of equipment, including encoders and transcoders, for digital television distribution, that in many cases does not support the MPEG-2 and other complementary splicing syntax. It would not be economical to redesign and replace such existing equipment to support the MPEG-2 splicing format.
Accordingly, it would be desirable to provide a system for inserting commercials in a digital television transport stream that is compatible with the operational aspects of pre-existing cue tones in analog television signals.
The system should avoid the need to decode and re-encode several data layers in a digital transport stream to obtain information regarding timing and buffer fullness status to allow a successful commercial insertion, thereby simplify and reducing the costs of required insertion equipment.
The system should be backward-compatible with equipment such as encoders, transcoders, and the like, that are already deployed by various cable television and satellite television service providers. Moreover, the system should be able to be implemented with only minor firmware upgrades to existing equipment, which is particularly advantageous when compared to integrated commercial insertion solutions.
The system should allow the use of splicers of varying seamless splicing capability, and should have a relatively minimal impact on the other devices at the uplink or headend (e.g., encoder, transcoder).
The system should further allow add/drop multiplexing prior to, or as part of, commercial insertion.
The system should provide compatibility between satellite television uplinks and cable television headends.
The system should ensure that decoders in consumers"" homes are splice-unaware (i.e., unaware of the presence of spliced data). This is to avoid having to replace these decoders and to prevent the enabling of xe2x80x9ccommercial killerxe2x80x9d devices which detect and block out commercials.
The system is preferably compatible with constant bit rate (CBR) and variable bit rate (e.g., including statistically multiplexed) streams. In other words, the inserter, depending on its type may operate on CBR streams for insertion, or add/drop (insert) into statistically multiplexed streams. The system described herein applies to both cases.
The present invention provides a system having the above and other advantages.
The invention relates to a system for inserting commercials into a digital television signal using cue commands. A cue command is functionally analogous to a cue tone but instead of a dual-tone multifrequency (DTMF) implementation of the cue_tone, it is implemented as a protocol message that is understood by the inserters (splicers).
A method for inserting digital commercials into a digital audiovisual bitstream includes the steps of: processing a first audiovisual signal to determine whether cue tones are present therein, encoding the first audiovisual signal as a digital spliceable data stream, and providing cue commands corresponding to the cue tones, if present, in the digital spliceable data stream. The cue commands indicate splicing points for splicing a digital commercial into the digital spliceable data stream.
The term xe2x80x9caudiovisualxe2x80x9d is used to represent a signal including video, audio, and/or other data, including, but not limited, to a television signal.
The digital spliceable data stream is forwarded to a commercial inserter, which detects the cue commands and inserts a commercial into the digital spliceable data stream in response thereto at a splice point designated by a first detected cue command, and monitors the digital spliceable data stream for a subsequent cue command to splice back from the inserted commercial to the original digital spliceable data stream.
A plurality -of single video program transport streams, including the digital spliceable data stream, may be multiplexed into a multi-program transport stream, and the multi-program transport stream forwarded to the commercial inserter.
In this case, the multi-program transport stream is forwarded to a commercial inserter, which detects the cue commands and inserts a commercial into the digital spliceable data stream in response thereto at a splice point designated by a first detected cue command, and monitors the multi-program transport stream for a subsequent cue command to splice back from the inserted commercial to the multi-program transport stream.
The first audiovisual signal may be an analog signal, in which case it is digitized and compressed to provide the digital spliceable data stream.
The cue commands are provided at the uplink site, or a remote studio site, while the commercials may be inserted at the uplink site and/or at a headend. In some cases, the digital audiovisual signal is originated locally from a server located in the headend.
Preferably, the cue commands are provided as a message in the digital spliceable data stream in a transport layer such that they may be readily detected by the inserter without having to decode several layers of the data stream.
Furthermore, the cue commands may designate desired or required program attributes of the inserted commercial, such as bit rate, and stream construct, such as number of audio streams, and the like.
Moreover, even if no cue tones are detected, the cue commands may be provided in response to a local network device, such as a real-time trigger or a scheduler/controller that is co-located or remotely located in a studio site.
An example syntax of such cue commands which may be used with the present invention is discussed in xe2x80x9cProposed SMPTE Standard for Televisionxe2x80x94Splice Points for MPEG-2 Transport Streams,xe2x80x9d SMPTE-312M, SMPTE Journal, October 1998., incorporated herein by reference.
The digital spliceable data stream may be a constant bit rate stream or a variable bit rate stream.
A corresponding apparatus is also presented.